Compact Root Architecture 2 Promotes Root Competence for Nodulation through the miR2111 Systemic Effector
Compact Root Architecture 2 Promotes Root Competence for Nodulation through the miR2111 Systemic Effector
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DOI：
10.1016/j.cub.2020.01.084
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发表时间：
2020-04-06
期刊：
影响因子：
9.2
通讯作者：
Frugier, Florian
中科院分区：
文献类型：
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作者：
Gautrat, Pierre;Laffont, Carole;Frugier, Florian
缺氮豆科植物形成新的根器官，根瘤，与固氮根瘤菌共生[1]。由于这种相互作用对植物有益，但具有高能量成本，因此根瘤形成由宿主植物通过系统途径（长距离作用）严格控制，以促进或限制根瘤菌感染和根瘤形成，这取决于早期感染和氮的可用性[2]。在蒺藜苜蓿模式豆科植物中，在根瘤化的根中产生的CLE 12（Clavata 3/胚周围区域12）和CLE 13信号肽通过SUNN（超级数字根瘤菌）受体在芽中起作用，以负调节根瘤化，从而自动调节根瘤数[3-5]。相反，在氮饥饿的根中产生的CEP（C-末端编码肽）信号肽通过CRA 2（紧凑根结构2）受体在芽中起作用，以促进在不存在根瘤菌的情况下已经发生的结瘤[6-9]。我们在这项研究中表明，这些系统性途径的下游芽到根信号传导效应子是芽产生的miR 2111 microRNA [10]，其负调控根中的TML 1（Too Much Love 1）和TML 2 [11 ]转录物积累，最终促进再生。低氮条件和CEP 1信号肽诱导在根瘤菌的情况下，生产的miR 2111依赖于CRA 2的活性在芽，从而有利于根的能力，为繁殖。当根被同化时，与SUNN途径一起负调节相同的miR 2111系统效应物，这允许通过氮可用性和根瘤菌线索动态微调豆科植物根的同化能力。
Nitrogen-deprived legume plants form new root organs, the nodules, following a symbiosis with nitrogen-fixing rhizobial bacteria [1] . Because this interaction is beneficial for the plant but has a high energetic cost, nodulation is tightly controlled by host plants through systemic pathways (acting at long distance) to promote or limit rhizobial infections and nodulation depending on earlier infections and on nitrogen availability [2]. In the Medicago truncatula model legume, CLE12 (Clavata3/Embryo surrounding region 12) and CLE13 signaling peptides produced in nodulated roots act in shoots through the SUNN (Super Numeric Nodule) receptor to negatively regulate nodulation and therefore autoregulate nodule number [3-5]. Conversely, CEP (C-terminally Encoded Peptide) signaling peptides produced in nitrogen-starved roots act in shoots through the CRA2 (Compact Root Architecture 2) receptor to promote nodulation already in the absence of rhizobia [6-9]. We show in this study that a downstream shoot-to-root signaling effector of these systemic pathways is the shoot-produced miR2111 microRNA [10] that negatively regulates TML1 (Too Much Love 1) and TML2 [11 ] transcripts accumulation in roots, ultimately promoting nodulation. Low nitrogen conditions and CEP1 signaling peptides induce in the absence of rhizobia the production of miR2111 depending on CRA2 activity in shoots, thus favoring root competence for nodulation. Together with the SUNN pathway negatively regulating the same miR2111 systemic effector when roots are nodulated, this allows a dynamic fine-tuning of the nodulation capacity of legume roots by nitrogen availability and rhizobial cues.